This invention relates to upgrading hydrocarbons to produce a high-quality naphtha fraction. More particularly, it pertains to hydrocracking highly aromatic light cycle oil in the presence of zeolite MCM-22 catalyst to produce a high octane gasoline.
As the demand for high quality gasolines increases, petroleum refineries are finding it necessary to convert increasingly greater proportions of crude oil to premium high octane fuels.
Catalytic hydrocracking processes have proven useful for converting heavy feedstocks such as gas oils and cycle oils to naphthas and middle range distillates such as diesel and jet fuels. Catalytic cracking without hydrogen is not able to effectively convert aromatic compounds, which are highly refractory. Hydrocracking, on the other hand, has proven effective in converting the refractory aromatic effluents from the catalytic crackers into premium gasoline. Fortuitously, the hydrogen necessary for hydrocracking is largely provided by another refinery process, i.e., reforming.
The added hydrogen saturates the aromatic carbon bonds thereby converting aromatics to cycloparaffins which can then undergo ring scission and dealkylation. Polynuclear aromatics, such as anthracene can be reduced to mononuclear aromatics (e.g. benzene, toluene, etc.), paraffins, and cycloparaffins.
U.S. Pat. No. 4,305,808 (Bowes et al.) discloses a catalytic hydrocracking process for converting polynuclear aromatic containing feedstock by contacting with a zeolite catalyst.
U.S. Pat. No. 3,130,007 discloses the preparation of zeolite Y. Zeolite Y is now standardly prepared in a modified form, ultra-stable Y (USY) which is used in various hydrocarbon conversion processes.
U.S. Pat. No. 4,738,766 (Fischer et al.) discloses a moderate pressure hydrocracking process in which a highly aromatic feedstock having a boiling range between 300.degree. F. and 650.degree. F. is processed to high octane gasoline by hydrocracking over a large pore catalyst such as Zeolite Y.
U.S. Pat. No. 4,764,266 (Chen et al.) describes a hydroprocessing scheme in which high boiling fractions such as gas oil and cracked cycle oils are converted into jet fuels and naphthas suitable for reforming into high octane gasoline by hydrocracking with a large pore zeolite X or zeolite Y catalyst, followed by hydroprocessing with zeolite beta.